The present application describes systems and techniques relating to handling packets defined by optical signals in a machine network.
A machine network is a collection of nodes coupled together with wired and/or wireless communication links, such as coax cable, fiber optics and radio frequency bands. A machine network may be a single network or a collection of networks (e.g., an internetwork, such as the Internet), and may use multiple networking protocols, including internetworking protocols (e.g., Internet Protocol (IP)). These protocols define the manner in which information is prepared for transmission through the network, and typically involve breaking data into segments generically known as packets (e.g., IP packets, ATM (Asynchronous Transfer Mode) cells) for transmission. A node may be any machine capable of communicating with other nodes over the communication links using one or more of the networking protocols.
The networking protocols are typically organized by a network architecture having multiple layers, where each layer provides communication services to the layer above it. A layered network architecture is commonly referred to as a protocol stack or network stack, where each layer of the stack has one or more protocols that provide specific services. The protocols may include shared-line protocols such as in Ethernet networks, connection-oriented switching protocols such as in ATM networks, and/or connectionless packet-switched protocols such as in IP.
Typically, many of the sub-networks in a network are wire-based electronic networks. But for long-haul connections, the networks being used are increasingly fiber-based optical networks (e.g., SONET and Synchronous Digital Hierarchy (SDH) based networks) connected with existing networks. IP routers are currently used in such optical networks. Many such routers receive packets as optical signals, convert them to electronic signals, compare destination addresses to a list of addresses or address prefixes in a forwarding table, modify their headers, send the packets to selected output interfaces, and convert back to optical signals.
In optical networks, wavelength-division multiplexing (WDM) can be used to increase link speeds. Often associated with WDM is the idea of an “all-optical network,” which offers ingress-to-egress transport of data without intervening optelectronic conversions, thus promising potential reductions in end-to-end latency and data loss as well as potential improvements in throughput. Some routers have been enhanced by wavelength-selective optical crossconnect switches and label-switching software, which maps flows of IP packets to lightpaths of WDM channels created dynamically between specific packet-forwarding endpoints. Label switching for optical networks is being developed as various standards such as Multiprotocol Label Switching (MPLS), Multiprotocol Lambda Switching (MPXS) and Simple Wavelength Assignment Protocol (SWAP).
In an attempt to overcome the high latency of lightpath establishment typical in optical label switching, optical burst switching (OBS) and Terabit Burst Switching (TBS) have been considered as alternative methods of exploiting WDM. The first of a stream of packets destined for one address can blaze a path through the network by setting up segments of the lightpath as it is being electronically routed, succeeding packets in the stream use this lightpath, and the lightpath is torn down later, either by a packet or implicitly by a time-out.